HI All
Finished up the latest radio project a Philco 49-506, I've noticed on almost all of the philco table top radios, for some reason they don't work worth a darn unless you have their Loop Antennas connected, strange, all of my other radios work with nothing more than a wire hooked too them, granted they work better with the Loop, but Philco's for some reason don't seem to be that way, the minute you connect the Loop Antenna on them they work perfectly, does anyone have an answer for this, I'm stumped, unless it has too do with the way the front end is set up on them?
Mark

Hi, Mark. To me the mystery is why you've found the non-Philco's to work without their loop antennas.

Such sets use the loop as the parallel inductance that is tuned into resonance by the variable tuning cap. The loop is also the antenna coil. Without the loop, there won't be resonance at any particular frequency. The whole RF spectrum gets fed into the 1st RF stage. The only tuning will be by varying the oscillator frequency.

:HI All
: Finished up the latest radio project a Philco 49-506, I've noticed on almost all of the philco table top radios, for some reason they don't work worth a darn unless you have their Loop Antennas connected, strange, all of my other radios work with nothing more than a wire hooked too them, granted they work better with the Loop, but Philco's for some reason don't seem to be that way, the minute you connect the Loop Antenna on them they work perfectly, does anyone have an answer for this, I'm stumped, unless it has too do with the way the front end is set up on them?
:Mark
:

:Hi, Mark. To me the mystery is why you've found the non-Philco's to work without their loop antennas.
:
:Such sets use the loop as the parallel inductance that is tuned into resonance by the variable tuning cap. The loop is also the antenna coil. Without the loop, there won't be resonance at any particular frequency. The whole RF spectrum gets fed into the 1st RF stage. The only tuning will be by varying the oscillator frequency.
:
::HI All
:: Finished up the latest radio project a Philco 49-506, I've noticed on almost all of the philco table top radios, for some reason they don't work worth a darn unless you have their Loop Antennas connected, strange, all of my other radios work with nothing more than a wire hooked too them, granted they work better with the Loop, but Philco's for some reason don't seem to be that way, the minute you connect the Loop Antenna on them they work perfectly, does anyone have an answer for this, I'm stumped, unless it has too do with the way the front end is set up on them?
::Mark
::Hi Doug
Yep its a mystery too me as well, I can't explain it either, they do work better with the Loop, but will pick up with out them also, my guess is, possibly Philco has a much tighter tuning and resonance than the others, thats my best guess, just thought I would pose the question, really weird huh?
Mark

Mark/Doug,
I'm not surprised that a tuned circuit such as the secondary of the antenna transformer (loop) performs much better at resonance than an untuned circuit such as a long wire. Now if one were to lightly couple a long wire antenna to the primary of the loop in such a way as to minimize de-tuning effects at the secondary, it would perform even better. Philco made some damn fine radios in their heyday, and I've had many pleasant experiences with them. You may notice that as VHF TV and FM radio came on the scene, the antenna input circuit(s) were much more elaborate and refined, the antennas were cut to lengths specific to frequency of use, impedances were matched for maximum power transfer to gulp every last bit of electromagnetic energy from the broadcast wave front. I believe in the later days of AM radio popularity, many high quality mfrs were attempting to refine their input circuits in the same way. As the popularity exploded, so did the radiated power. In the interest of economy, the RF amplifier stages were removed and replaced with a single tuned circuit feeding the converter directly. If one were to facilitate the construction of the ultimate AM radio, one or more tuned RF stages (like the old TRF's)preceding the converter would greatly improve performance. A sort of pre-selector, not so much for the gain, but bandwidth limiting considerations, image rejection etc. A high quality car radio of yesteryear performed pretty much inside a ferrous metal enclosure, and historically an interference free environment (except ignition noise), and were typically further contained in their own ferrous metal enclosure. Is it any wonder that their performance far exceeded the plastic/bakelite line operated table model most of the time. I haven't taken the opportunity to research it, but suspect no present day common AM radios contain tuned RF amplifier stages ahead of the converter.

marv

::Hi, Mark. To me the mystery is why you've found the non-Philco's to work without their loop antennas.
::
::Such sets use the loop as the parallel inductance that is tuned into resonance by the variable tuning cap. The loop is also the antenna coil. Without the loop, there won't be resonance at any particular frequency. The whole RF spectrum gets fed into the 1st RF stage. The only tuning will be by varying the oscillator frequency.
::
:::HI All
::: Finished up the latest radio project a Philco 49-506, I've noticed on almost all of the philco table top radios, for some reason they don't work worth a darn unless you have their Loop Antennas connected, strange, all of my other radios work with nothing more than a wire hooked too them, granted they work better with the Loop, but Philco's for some reason don't seem to be that way, the minute you connect the Loop Antenna on them they work perfectly, does anyone have an answer for this, I'm stumped, unless it has too do with the way the front end is set up on them?
:::Mark
:::Hi Doug
: Yep its a mystery too me as well, I can't explain it either, they do work better with the Loop, but will pick up with out them also, my guess is, possibly Philco has a much tighter tuning and resonance than the others, thats my best guess, just thought I would pose the question, really weird huh?
:Mark
:

:Mark/Doug,
:I'm not surprised that a tuned circuit such as the secondary of the antenna transformer (loop) performs much better at resonance than an untuned circuit such as a long wire. Now if one were to lightly couple a long wire antenna to the primary of the loop in such a way as to minimize de-tuning effects at the secondary, it would perform even better. Philco made some damn fine radios in their heyday, and I've had many pleasant experiences with them. You may notice that as VHF TV and FM radio came on the scene, the antenna input circuit(s) were much more elaborate and refined, the antennas were cut to lengths specific to frequency of use, impedances were matched for maximum power transfer to gulp every last bit of electromagnetic energy from the broadcast wave front. I believe in the later days of AM radio popularity, many high quality mfrs were attempting to refine their input circuits in the same way. As the popularity exploded, so did the radiated power. In the interest of economy, the RF amplifier stages were removed and replaced with a single tuned circuit feeding the converter directly. If one were to facilitate the construction of the ultimate AM radio, one or more tuned RF stages (like the old TRF's)preceding the converter would greatly improve performance. A sort of pre-selector, not so much for the gain, but bandwidth limiting considerations, image rejection etc. A high quality car radio of yesteryear performed pretty much inside a ferrous metal enclosure, and historically an interference free environment (except ignition noise), and were typically further contained in their own ferrous metal enclosure. Is it any wonder that their performance far exceeded the plastic/bakelite line operated table model most of the time. I haven't taken the opportunity to research it, but suspect no present day common AM radios contain tuned RF amplifier stages ahead of the converter.
:
:marv
:
:
:
:::Hi, Mark. To me the mystery is why you've found the non-Philco's to work without their loop antennas.
:::
:::Such sets use the loop as the parallel inductance that is tuned into resonance by the variable tuning cap. The loop is also the antenna coil. Without the loop, there won't be resonance at any particular frequency. The whole RF spectrum gets fed into the 1st RF stage. The only tuning will be by varying the oscillator frequency.
:::
::::HI All
:::: Finished up the latest radio project a Philco 49-506, I've noticed on almost all of the philco table top radios, for some reason they don't work worth a darn unless you have their Loop Antennas connected, strange, all of my other radios work with nothing more than a wire hooked too them, granted they work better with the Loop, but Philco's for some reason don't seem to be that way, the minute you connect the Loop Antenna on them they work perfectly, does anyone have an answer for this, I'm stumped, unless it has too do with the way the front end is set up on them?
::::Mark
::::Hi Doug
:: Yep its a mystery too me as well, I can't explain it either, they do work better with the Loop, but will pick up with out them also, my guess is, possibly Philco has a much tighter tuning and resonance than the others, thats my best guess, just thought I would pose the question, really weird huh?
::Mark
::Hi Marv
I would agree with your theory, makes alot of sense, I finished her up today! really impressed! everything fit great!, I had too use a 48-200 chassis in this 49-506, the original chassis was totally destroyed behond restoration, I have too hand it too Ford they were really good about keeping the chassis the same for most of these Transitone radios, made it easy too swap out one for the other, this radio looks prestine now and sounds the same! really cool:)
Mark